Imagine getting into a crowded Mumbai local during peak hours. Thousands of people on the platform along with you and hundreds inside the train. You got to get into the train to reach home in time. You experience people pushing you from behind making it difficult to get in comfortably. The train folks are resisting you from getting into the already crowded compartment. Already tired, right?
This is the best example to understand Impedance. Impedance is similar to Resistance.
If you hated Physics, let me throw a physics bomb your way.
Resistance(R) is the opposition to Current (I) on every applied Voltage. If you can recollect Ohm’s law from High School Physics, it said V=IR. That means R=V/I.
Now comparing to the train example, there were two resisting factors, people pushing from outside and inside. The total amount of Resistance you face from outside and inside is the Impedance. Impedance, like Resistance, is measured in ohms.
How the hell does this matter to you while using a headphone?
As you know, Headphones have driver units that are its speakers. These speakers have magnets that help generate sound in the headphone. These magnets require current to run.
You can never stop a kid from playing, can you? Only an ice-cream can. Consider his urge to play the resistance. Ice-cream can cross that resistance. So, a proper amount of current is required to cross the impedance and generate electricity of required magnitude.
When it comes to headphones, have you ever wondered why impedance plays an important role? Headphone is just a smaller speaker for you to listen to personally. Loudspeakers need to give huge output, so their impedance is mapped at 4, 6 or 8 ohms. Headphones being smaller and needing lesser sound output have impedance ranging from 15 to 35 ohms, in general.
The earphones and headphones you use along with your phone or computer have impedance in this range. This limits the Audio output to stay under 1000mW. This is more than enough for portable headphones.
What about the headphones having higher impedance? Why can’t they be used with mobile devices?
Simple, your phone and laptop don’t have the power to power those headphones.
Amplification comes into the picture here. What do you do when a door won’t open? Simply apply more force. Amplification is required for Headphone drivers having impedance above 35 ohms.
There are different amplifiers made to match headphones of that impedance to get the proper amplified output.
Why the need for higher impedance? Why the need for headphone amplifiers?
The relation between impedance and loudness is inversely proportionate. Lesser the impedance, higher the output volume. This is not always the case when caring about quality of output.
It is considered, higher the impedance better the audio quality. This statement is not always true. Headphones having 35 ohms impedance are also used for professional setups as they sound excellent. How to justify this statement?
Speaker drivers having higher impedance are made up of better materials. This may give better audio quality when playing high quality audio files. It helps maintain the Audio fidelity, making the audio sound more original. Another reason professional and audiophile headphones have high impedance is to protect them from actually blowing up when connected to high power sources. DJ turntables, Audio Mixers, Audio boxes have powered jacks, which may cause harm to low impedance headphones.
Do you get it now? Why there are headphones and earphones having different impedance levels?
Let’s simplify it, What do you need?
If you are listening to music from a portable device like mobile phone, laptop, ipod and other players, all you need is a earphone or headphone having low impedance.
If you are a professional or audiophile, i don’t need to tell you. High impedance Headphones of course. Music is what matters at last.